Prevention of rust and corrosion



United States Patent G 1 2,888,401 PREVENTION OF RUST AND. CORROSION William B. Hughes, Webster Groves, and Verner L, Stromberg, Shrewsbury, Ma, assignors to Petrolite Corporation, Wilmington, DeL, a corporation of Delaware No Drawing. Application February 6, 1957 Serial No. 638,429

9 Claims. (Cl. 252-855) The present invention is concerned with the process of preventing corrosion of ferrous metals by means of partial estersv of polymerized fatty acids, particularly dimerized and trimerized fatty acids and greater emphasis on the dimerized fatty acids because of their greater ability and their cost. The esters are derived from saturated or unsaturated monohydric alcohols having a reactive primary or secondary hydroxy group.

' More specifically, the present invention is concerned with a method for inhibiting the corrosion of ferrous metals by hydrocarbon fluids which are inherently corrosive in nature due to the presence of one or more materials of the kind recognized to be corrosive such as hydrocarbon fluids containing water, hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms, etc., and combinations of such corrosion causing substances either alone or in combination with other corrosive materials such as, for example, oxygen, etc., andparticularly in presence of both water and oxygen.

Generally speaking, one of the principal applications is in the primary production of petroleum by reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and hydrogen sulfide which comprises introducing into said fluid a corrosion inhibiting compound of the kind herein described.

However, in secondary recovery processes, i.e., such as flooding processes and particularly where flood water is used over again and again, it is not unusual to have oxygen present although oxygen may occur in a refining or transportation system by mere leakage and thus the invention from this particular standpoint can be restated as a method of inhibiting corrosion of ferrous metals by hydrocarbon fluids.

More specifically, the present invention is concerned with a method for inhibiting corrosion of ferrous metals by hydrocarbon fluids containing water and a member of the group of corrosive materials consisting of hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms per molecule, combinations of these materials with each other, combinations of each of said corrosive materials with oxygen, and combinations of said materials with each other and oxygen, comprising adding to said fluids at least 5 parts per million of a partial ester of a polymerized unsaturated higher fatty acid, obtained by polymerization not greater than the trimeric stage and further characterized by the fact that the precursory unsaturated fatty acid contains from 6 to 22 carbon atoms and has from 2 to 3 ethylenic linkages per molecule; said partial ester characterized by the fact that at least one carboxylic hydrogen atom is replaced by the alcoho'lic residue of a monohydric alcohol selected from the class of aliphatic and cycloaliphatic alcohols having not over 26 carbon atoms.

The herein described corrosion inhibitor is particularly effective as a corrosion inhibiting agent in the oil industry. The use of such corrosion inhibitors is common practice. See, for example, U.S. Patents Nos. 2,736,658, dated. February 28, 1956 to Pfohl et al., 2,756,211, dated July 24, 19,56, and 2,727,003, dated December 13, 1955, both to 2v Hughes, and also U.S. Patent 2,614,980 to Lytle, dated October 21, 1952.

As to the employment of corrosion inhibiting agents in the petroleum industry one need only refer to 'ex-' cerpts from the above patents as clearly indicating the field of application.

Reference is made to an excerpt from aforementioned U.S. Patent 2,727,003 which also applies with equal force and effect in regard to the instant invention:

It should also be pointed out that the corrosiveness of oil well brines will vary from well to well, and the proportion of corrosion inhibiting agent added to the well fluids should also be varied from well to well. Thus, in. some wells it may be possible to effectively control corrosion by the addition of as little as 10 p.p.m. of my new compositions to the well fluids, whereas in other wells, it may be necessary to add 200 p.p.m. or more.

In using my improved compositions for protecting oil well tubing, casing, andother equipment which comes in contact with the corrosive oil-brine production, I findthat excellent results may be obtained by injecting an appropriate quantity of a selected composition into a producing well so that it may mingle with the oil-brine mix. ture and come into contact with the casing, tubing, pumps and other producing equipment. I may, for example, introduce the inhibiting composition into the top of the casing, thus causing it to flow down into the well. and,

thence back through the tubing, etc. In general, I have found that this procedure sufiices to inhibit corrosion throughout the entire system of production, and collection, even including field tankage.

As matter of fact, what is said above is in essence the equivalent of what appears in U.S. Patent Re. 23,227, dated May 9, 1950, to Blair et al. at columns 9, 10, and 11.

Specific reference is made to aforementioned U.S. Patent 2,756,211. Indeed, with a slight change in text. the following is essentially a'verbatim excerpt of a para, graph in said patent:

In case serious emulsion or gel problems are encountered, demulsifiers may be added. This is important not only to avoid the troublesome emulsions and gels themselves, but also to improve corrosion inhibition. The explanation of less effective corrosion inhibition in the presence of emulsions apparently is that the inhibitor is some- What surface-active. That is, it is concentrated at interfacial surfaces. Since this surface is great in an emulsion, most of the inhibitor will be concentrated in these inter-. faces and little will remain in the body of the oil for deposition on the metal surfaces. In many Wells, oil-inwater type emulsions often occur naturally. In such Wells, the inhibitors herein described tending to form Water-in-oil type emulsions, often decrease the emulsion problems naturally present. Thus, in addition to being effective corrosion inhibitors the herein described products tend to eliminate emulsion problems which sometimes appear when some of the present day inhibitors are used in oil wells or refinery processing.

Polymerized unsaturated fatty acids previously referred to and limited to dimers and trimers, are derived by conventional methods from dienoic and trienoic fatty acids. They may be illustrated for convenience by reference to the dimerized acids although in the preferred type, i.e., derived from the higher fatty acids having 18 to 22 carbon atoms the trimeric acids are as suitable as the dimeric acids and, in fact, mixtures of the two may be employed. I

However, such acids and particularly the dimerized ones are readily prepared from dior trienoic fatty acids having the general formula 3 where n is an integer of from 5 to 21 and x is 3 to 5. As will be evident, such monomeric acids contain from 6 to 22 carbon atoms and may contain 2 to 3 ethylenic linkages as the ratio of carbon to hydrogen increases, i.e., as x increases from 3 to 5. Dimerized acids corresponding to the addition products of the foregoing acids therefore may be defined by the general formula:

where n is an integer of from 10 to 42 and where x is an integer of from 6 to 10. These dimeric acids are therefore dibasic or dicarboxylic acids having from 12 to 44 carbon atoms.

Representative members of the class of dimerized acids capable of forming the compounds of this invention are dimers of dienoic acids such as sorbic (hexadienoic), linoleic (octadecadienoic), humoceric (nonadecadienoic) and eicosinic (eicosadienoic) acids. Dimers of trienoic acids, for example, linolenic and eleostearic (octadecatrienoic) acids also may be used.

For convenience, what is said hereinafter is divided into three parts.

Part one is concerned with the reagents employed, i.e., the acids and alcohols.

Part two is concerned with the preparation of partial esters following the conventional procedure.

Part three is concerned with the use of such partial esters for corrosion inhibition and includes data in regard to a number of tests which clearly demonstate the effectiveness of the herein described partial esters.

PART ONE A variety of dimerized fatty acids have been obtained and are described in the patent literature. See, for example, U.S. Patent No. 2,417,739, dated March 18, 1947, to De Groote, and more particularly US. Patent No. 2,632,695, dated March 24, 1953, to Landis et a1.

-Dirnerized acids have been obtained from fish oil fatty acids in which the total number of carbon atoms may have varied from 20 to 24 and thus the dimerized acids may have as many as 44, or even more, carbon atoms. The same applies to certain dimerized acids obtained from the oxidation of wax. Furthermore, esters of dimerized acids have been reacted with aromatic materials such as alkylated or polyalkylated naphthalene in the presence of aluminum chloride, or the like, to yield dicarboxy acids having as many as 50 carbon atoms.

Referring to a consideration of dimeric fatty acids one may illustrate this structure by the following composition:

The acids produced commerically run approximately 85% or better dimer content with some trimer and some monomer. As pointed out in aforementioned U.S. Patent No. 2,632,695, a well-known source of these dimeric acids is the product sold by Emery Industries, Inc., and said to be dilinoleic acid. In the literature published by the Emery Industries, Inc., the properties of this product are given as follows:

Neutral equivalent 290-310.

Iodine value -95.

Color Gardner 12 (max). Dimer content Approx. Trimmer and higher Approx. 12%. Monomer Approx. 3%.

The above product was formerly sold at Emery 955 Dimer Acid. Subsequently the maker designated the product as Empol 1022. See what is said subsequently in regard to a recently available Empol 1022 from the same maker. 1

One can obtain polymerized fatty acids which are essentially tribasic in character with a minor amount of C diabasic acid present. One source of this material is Emery Industries, Inc., Cincinnati, Ohio, who describe their particular product as Emery 3055-8 Polymerized Fatty Acid. This is typical of any such trirnerized fatty acid and it is primary C tribasic acid, with a minor amount of C dibasic acid being present. It is characterized by a high viscosity and possesses a dark color. Because of its high functionality it follows that this material should be useful as an intermediate for the production of 3 dimensional polymers and high molecular weight mono esters.

Typical characteristics:

One need not employ products which are essentially dimeric or essentially trimeric. In fact, a mixture can be employed advantageously. There are also available in the open market polymerized fatty acids which are approximately one-half to two-thirds dimeric and the remainder trimeric. Or, if one wishes one can make a mixture of dimeric and trimeric acids as, for example, in equimolar proportions.

Reference is made to Table I in which the reactant happened to be the original Emery 955 Dimer Acid previously described which at one time, as noted, was subsequently designated as Empol 1022. However, at the present time the product sold by the same company designated by the name Empol 1022 is slightly different insofar that the trimer content is somewhat higher. The characteristics are as follows:

Acid value, Mg KOH per gram min. Saponification value, Mg KOH per gram min. Unsaponifiable 2.0% max. Neutralization equivalent 289-304. Dimer content 75%. Trimer content 22%. Monomer content 3%.

All the products described in Table I subsequently have been prepared with this modified version of 955 Dimer Acid and the products obtained are at least as good as, or in many instances better than the products originally prepared from the old Emery 955 Dimer Acid.

The partial esters are prepared from monohydric alcohols or the equivalent of the same kind that have been used for comparable esters of low molal fatty acids and high molal fatty acids, or comparable products. They include the monohydric alcohols having from one to 24 carbon atoms such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, octyl alcohol, decyl alcohol, oleyl alcohol, alcohols of higher fatty acids and mixed fatty acids including not only those which have as many as 18 carbon atoms but the alcohols derived from behemic, lignoceric and cerotic acids. The alcohols may be straight chain or branched, provided only the hydroxyl group is a secondary or primary hydroxyl and preferably the latter.

, Dimerized or trimerized fatty acids, or mixtures of same, can be converted into partial esters by use of the well known procedure employed to produce esters of monocarboxy and polycarboxy acid. Needles to say, the polymerized acids could be converted into derivatives suchgas acyl chloride low molal esters, the anhydride or any other suitable equivalent for ester manufacture. However, from a practical standpoint they can be prepared very readily from the acids and thus subsequent illustrations will include the use of acids themselves, also, anyequivalent that can be used.

PART TWO Since the production of partial esters of the kind herein described involves nothing more than conventional procedure it is not believed that examples are necessary, but for the purpose of illustration, the following examples are included:

Example 1 Example 2 This reaction was allowed to proceed as in Example 1 except stearyl alcohol, 270 grams, was used in place of the lauryl alcohol. Three" and one-half hours was necessary to complete this reaction.

Example 3 This reaction was allowed to proceed as in Example 1 except that 130 grams of Indoil Chemical Companys isooctyl alcohol was used in place of the lauryl alcohol. Five hours were required to complete the reaction.

Table I Molecular Reaction Acid Alcohol Ratio Time in Hours Emer 955 dimer acid Lauryl 1:1 3 DY). Stearyl 1:1 3% Isooctyl 1:1 5 Benzyl 1:1 12 Cyclohexyl. 1 1 6 molcyl 1:1 5 Do yl 1:1 5 Rohm & Haas VR-l" acid l ooctyl 1:1 5 Emery 3055 S (trirner acid) Lauryl 1:1 3 Do .do 1:2 I Do Isooctyl 1:1 4 Do. do 1:2 12 D0 Oyclohexyl--. 1:1 18 Do. do 1:2 30 Do Oleyl 1:1 8 D0 do 1:2 9

"As to a description of VR1 acid and with particular reference to its chemical characteristics, see the description not only of VR-l acid but also of VR acid in U.S. Patent No. 2,773,879 dated December 11, 1956, to Sterlin, with particular reference to the subject matter m col4umns and 5.

6 Example 4 This reaction'was allowed to proceed as in Example 1 except that 108 grams of benzyl alcohol were used in place of the lauryl alcohol. Twelve hours were required to complete the reaction.

Example 5 This reaction was allowed to proceed as in Example 1 except that grams of cyclohexanol were used in place of the lauryl alcohol. Six hours were required to complete the reaction.

The products as herein described have very good solubility for the uses indicated. Solutions in alcohols and aromatic solvents; benzene, toluene, etc.; may readily be prepared. Example #1 indicates a 50% xylene solution of the product. Solutions of 50% or less of materials prepared in Examples 1, 2, 3, 4 or 5 may be prepared using benzene, xylene, isopropyl alcohol, xylene, etc.

PART THREE The etfectiveness of these compositions in inhibiting the corrosion of metal may be better and more fully understood by reference to certain tests which have been conducted. The test procedure, as hereafter described,

involved a measurement of the corrosive action of corrosive fluids under dynamic conditions at elevated temperatures with the rate of corrosion being measured by the increase in the iron content of the corrosive brine. This procedure is considered sound since the .loss of weight of metal must be accompanied by a gain in the iron content of the solution.

In testing the compositions 400 ml. of 10% sodium chloride solution containing 50 p.p.m, acetic acid and 100 ml. of kerosene were charged to a beaker and the liquids were heated to F. One inch square coupons made of 18 gauge mild steel which had been cleaned by sand blasting were used. The coupons were suspended by glass hooks in a position below the normal oilwater interface. The liquids were stirred and iron content of the water was determined at five-minute intervals for a thirty-minute period. After this time a comparison between the iron content of an inhibited and an uninhibited test allowed the evaluation of the protection afforded by the inhibitor which was reported as percent protection. The percent protection figure was calculated from the iron content of the brine after a thirtyminute exposure to the metal. Thus, protection per centage was calculated for each system according to the following formula:

(Fe Blank)( Fe Sample) WX Protection Table II DIMERIZED ACID COMPOSITIONS PPegcefnt r0 ec 1on Inhibitor Composition 20 40 p.p.m. p.p.m.

Dimer Acid Oleyl Alcohol 1:1 65 90 Dimer Acid Oleyl Alcohol l:2. 0 0 Dimer Acid Lanryl Alcohol 1:1 50 61 Dimer Acid Lauryl Alcohol l:2 O 0 Dimer Acid Stearyl Alcohol 1:1. 0 59 Dimer Acid iso Octyl Alcohol 1:1 4 75 Dimer Acid Benzyl Alcohol 1:l 0 4:7 Dimer Acid Cyclohexyl Alcohol 1 0 50 VR-l Acid 0 31 955 Acid 0 33' Table III TRIMERIZED ACID COMPOSITIONS In using these improved compositions for protecting oil or gas producing equipment which comes in contact with corrosive materials excellent results may be obtained by injecting an appropriate quantity of a selected composition into the producing well so that it may mingle with the produced fluids and come in contact with the casing, tubing, pumps and other producing equipment. It may, for example, be introduced as a solution in a suitable solvent into the top of the casing, thus causing it to flow down the annular space and thence back through the tubing, etc. In general it has been found that this procedure sufiices to inhibit corrosion throughout the entire system of production, and collection, even including field tankage.

It should be pointed out that the corrosiveness of produced or transported fluids will vary greatly from one environment to another and the proportion of corrosion inhibiting agent required to effectively protect each system will also vary. Thus, it may be possible to effectively control corrosion in some systems by the addition of as little as ppm. of one of the described compositions while in other systems it may be necessary to add 200 ppm. or more.

It may be desirable to convert these new compositions into solid sticks by use of wax or other solid materials. Such sticks can be applied to gas condensate wells by means of special fittings at the well heads which will allow the solid stick to reach the bottom of the well, then dissolve slowly releasing the inhibitor into the producing stream over a period of time.

When applying these new compositions to gas pipelines it is desirable to meter a measured quantity of the selected inhibitor, as a solution, into the pipeline. The amount used will depend upon the volume being transported by the line and by the nature of that liquid. It is advisable to overtreat the line at first and gradually reduce the quantity of inhibitor to an efficient use concentration.

It is to be understood that the improved compositions may be used alone, but are not limited to use alone and may be employed along with other agents commonly introduced into the described corrosive situations for breaking emulsions, limiting scale formation, etc. It is further evident that the improved compositions are not restricted to use in the described systems but may be employed to perform this function in other places such as tankers, refineries, storage tanks or other places where corrosive brines may be met whether these brines are of naturally occurring origin or not.

The efficiency of these compounds can be further demonstrated by reference to certain tests. The technique for these tests is fully described in US. 2,466,517. By use of the improved compositions according to the technique employed in the above mentioned patent in column 8, lines through 45, but substituting a solution of the material described as 15 in Table III results which are substantially better would be evident.

Likewise using the same material in a wax-containing stick as described in the aforementioned patent in column 8, lines and following, substantially superior results to those described are possible.

Having thus described our invention, what we claim as new and desired to obtain by Letters Patent is:

1. A method of inhibiting corrosion of corrodible ferrous metals employed in the recovery, transportation and refining of petroleum hydrocarbon fluids; said hydrocarbon fluids containing water and a member of the group of corrosive materials consisting of hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms per molecule, combinations of these materials with oxygen, and combinations of said materials with each other and oxygen; said method comprising adding to said fluids at least 5 parts per million of a partial ester of a polymerized unsaturated higher fatty acid, obtained by polymerization not greater than the trimeric stage and further characterized by the fact that the precursory unsaturated fatty acid contains from 6 to 22 carbon atoms and has from 2 to 3 ethylenic linkages per molecule; said partial ester being characterized by the fact that at least one carboxylic hydrogen atom is present and at least one carboxylic hydrogen atom is replaced by the alcoholic residue of a monohydric alcohol selected from the class of aliphatic and cycloaliphatic alcohols having 6 to 26 carbon atoms.

2. A method of inhibiting corrosion of corrodible ferrous metals employed in the recovery, transportation and refining of petroleum hydrocarbon fluids; said hydrocarbon fluids containing water and a member of the group of corrosive materials consisting of hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms per molecule, combinations of these materials with oxygen, and combinations of said materials with each other and oxygen; said method comprising adding to said fluids at least 5 parts per million of a partial ester of a polymerized unsaturated higher fatty acid, derived from a precursory acid having at least 18 and not over 22 carbon atoms and corresponding to the formula (RCOO),,--R-(COOH),,,' in which R is the residual radical of said polymerized fatty acid, R is the residue of an aliphatic alcohol having 6 to 26 carbon atoms and n is a small whole number varying from 1 to 2 and n is a small whole number varying from 1 to 2, and with the further proviso that the sum of n and n is at least 2 and not over 3.

3. A method of inhibiting corrosion of eorrodible ferrous metals employed in the recovery, transportation and refining of petroleum hydrocarbon fluids; said hydrocarbon fluids containing water and a member of the group of corrosive materials consisting of hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms per molecule, combinations of these materials with oxygen, and combinations of said materials with each other and oxygen; said method comprising adding to said fluids at least 5 parts per million of a partial ester of a polymerized unsaturated higher fatty acid, having 18 carbon atoms andcorresponding to the formula in which R is a residual radical of said polymerized fatty acid, R is the residue of an aliphatic alcohol having 6 to 26 carbon atoms, n is a small whole number varying from 1 to 2 and n is a small whole number varying from 1 to 2, and with the further proviso that the sum of n and n is at least 2 and not over 3. 4. A method of inhibiting corrosion of corrodible ferrous metals employed in the recovery, transportation and refining of petroleum hydrocarbon fluids; said hydrocarbon fluids containing water and a member of the group of corrosive materials consisting of hydrogen sulfide, carbon dioxide, organic acids containing 2 to 4 carbon atoms per molecule, combinations of these materials with oxygen, and combinations of these materials with each.

other and oxygen; said method comprising adding to said fluids at least parts per million of a partial ester of a polymerized unsaturated higher fatty acid having 18 carbon atoms and corresponding to the formula in which R is a residual radical of said polymerized fatty acid, R is the residue of an aliphatic alcohol having 6 to 26 carbon atoms, n is a small whole number varying from 1 to 2 and n is a small whole number varying from 1 to 2, and with the further proviso that the sum of n and n is at least 2 and not over 3.

5. A method for reducing the corrosiveness to corrodi ble ferrous metal of the corrosive petroliferous well fluid including moisture and hydrogen sulfide; said method comprising adding to said fluids a partial ester of a polymerized unsaturated higher fatty acid having 18 carbon atoms and corresponding to the formula in which R is the residual radical of said polymerized fatty acid, R is the residue of an aliphatic alcohol having 6 to 26 carbon atoms, n is a small whole number varying from 1 to 2 and n is a small whole number varying from 1 to 2, and with the further proviso that the sum of n and n' is at least 2 and not over 3.

6. A method for reducing the conrosiveness to corrodible ferrous metal of the corrosive petroliferous well fluid including moisture and hydrogen sulfide; said method comprising adding to said fluids a partial ester of a polymerized unsaturated higher fatty acid having 18 carbon atoms and corresponding to the formula (R'COO),,-- (COOH),,' in which R is the residual radical of said polymerized fatty acid, R is the residue of an aliphatic alcohol having 6 to 26 carbon atoms, n is 1 and n is 1.

7. The method of claim 6 wherein R is the residual radical of dimeric fatty acids selected from the class consisting of and 11 4 95011 HC(OH 0-OH radical.

References Cited in the file of this patent UNITED STATES PATENTS 2,631,979 McDenmott Mar. 17, 1953 2,763,612 Raifsnider et a1. Sept. 18, 1956 2,767,144 Gottshall et al Oct. 16, 1956 

1. A METHOD OF INHIBITING CORROSION OF CORRODIBLE FERROUS METALS EMPLOYED IN THE RECOVERY, TRANSPORTATION AND REFINING OF PETROLEUM HYDROCARBON FLUIDS; SAID HYDROCARBON FLUIDS CONTAINING WATER AND A MEMBER OF THE GROUP OF CORROSIVE MATERIALS CONSISTING OF HYDROGEN SULFIDE, CARBON DIOXIDE, ORGANIC ACIDS CONTAINING 2 TO 4 CARBON ATOMS PER MOLECULE, COMBINATION OF THESE MATERIALS WITH OXYGEN, AND COMBINATIONS OF SAID MATERIALS WITH EACH OTHER AND OXYGEN; SAID METHOD COMPRISING ADDING TO SAID FLUIDS AT LEAST 5 PARTS PER MILLION OF A PAETIAL ESTER OF A POLYMERIZED UNSATURATED HIGHER FATTY ACIDS, OBTAINED BY POLYMERIZATION NOT GREATER THAN THE TRIMERIC STAGE AND FURTHER CHARACTERIZED BY THE FACT THAT THE PRECURSORY UNSATURATED FATTY ACID CONTAINS FROM 6 TO 22 CARBON ATOMS AND HAS FROM 2 TO 3 ETHYLENIC LINKAGES PER MOLECULE; SAID PARTIAL ESTER BEIN CHARACTERIZED BY THE FACT THAT AT LEAST ONE CARBOXYLIC HYDROGEN ATOM IS PRESENT AND AT LEAST ONE CARBOXYLIC HYDROGEN ATOMS IS REPLACED BY THE ALCOHOLIC RESIDUE OF A MONOHYDRIC ALCOHOLS SELECTED FROM THE CLASS OF ALIPHATIC AND CYCLOALIPHATIC ALCOHOLS HAVING 6 TO 26 CARBON ATOMS. 